The complete specification of assignment #3 can be found as part of the stream at iTunes.

Create a ball and get it to bounce off the walls

At one level, creating the ball is easy, given that it’s just a filled GOval. The interesting part lies in getting it to move and bounce appropriately. You are now past the “setup” phase and into the “play” phase of the game. To start, create a ball and put it in the center of the window. As you do so, keep in mind that the coordinates of the GOval do not specify the location of the center of the ball but rather its upper left corner. The mathematics is not any more difficult, but may be a bit less intuitive.
The program needs to keep track of the velocity of the ball, which consists of two separate components, which you will presumably declare as instance variables like this:

private double vx, vy;

Continue reading “cs106a – Assignment #3 – Task #3”

The complete specification of assignment #3 can be found as part of the stream at iTunes.

Create the paddle

The next step is to create the paddle. At one level, this is considerably easier than the bricks. There is only one paddle, which is a filled GRect. You even know its position relative to the bottom of the window.
The challenge in creating the paddle is to make it track the mouse. The technique is similar to that discussed in Chapter 9 for dragging an object around in the window. Here, however, you only have to pay attention to the x coordinate of the mouse because the y position of the paddle is fixed. The only additional wrinkle is that you should not let the paddle move off the edge of the window. Thus, you’ll have to check to see whether the x coordinate of the mouse would make the paddle extend beyond the boundary and change it if necessary to ensure that the entire paddle is visible in the window.

Continue reading “cs106a – Assignment #3 – Task #2”

The complete specification of assignment #3 can be found as part of the stream at iTunes.

Set up the bricks

Before you start playing the game, you have to set up the various pieces. Thus, it probably makes sense to implement the run method as two method calls: one that sets up the game and one that plays it. An important part of the setup consists of creating the rows of bricks at the top of the game, which look like this:

The number, dimensions, and spacing of the bricks are specified using named constants in the starter file, as is the distance from the top of the window to the first line of bricks. The only value you need to compute is the x coordinate of the first column, which should be chosen so that the bricks are centered in the window, with the leftover space divided equally on the left and right sides. The color of the bricks remain constant for two rows and run in the following rainbow-like sequence: RED, ORANGE, YELLOW, GREEN, CYAN.

Continue reading “cs106a – Assignment #3 – Task #1”